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황점식,Hwang, Jeomshik 한국해양학회 2012 바다 Vol.17 No.3
방사성탄소동위원소는 해양의 탄소순환을 이해하는 데 유용한 도구이다. 현재 가속질량분석기를 이용한 분석 기술의 발달로 유기물전체 뿐만 아니라 특정 유기화합물에서도 방사성탄소 분석이 이루어지고 있다. 이 리뷰 논문에서는 방사성탄소의 측정 방법과 농도 표현에 대하여 간단히 소개하고 방사성탄소를 해양의 유기탄소 순환 연구에 이용한 예들을 살펴보았다. 입자유기탄소와 용존유기탄소의 기원 물질 및 순환, 저서생물의 선택적 섭식, 입자유기물의 생화학적 화합물군의 거동, 분자크기에 따라 분류한 용존유기물군의 거동, 퇴적물의 수평 이동, 퇴적물의 연대측정, 육상기원 유기물의 거동, 미생물 유기물의 기원 물질, 할로겐화 유기물의 기원을 이해하기 위한 연구의 예들을 통하여 유기물전체, 유기물군, 특정 유기화합물의 방사성탄소 측정이 어떻게 해양 유기탄소 순환 연구에 활용될 수 있는지 기술하였다. Radiocarbon is a powerful tool for studies of carbon cycling in the ocean. Development of measurement technology of accelerator mass spectrometry has enabled researchers to measure radiocarbon even in specific compounds. In this paper, a brief introduction on radiocarbon measurement and reporting of radiocarbon data is provided. Researches that used radiocarbon measurements on bulk organic matter, organic compound classes, and specific organic compounds are reviewed. Examples include works to understand the cycling of particulate and dissolved organic matter, biochemical composition of particulate organic matter, post-depositional transport of sedimentary organic matter, selective incorporation of fresh organic matter by benthic organisms, chemoautotrophy by archaea, and sources of halogenated chemical compounds found in marine mammals.
서준형,서호종,황점식,김규범 한국해양과학기술원 2021 Ocean science journal Vol.56 No.4
Thorium-234 (Th-234; t(1/2) = 24.1 days) has been widely used as a tracer of particle settling and organic carbon export in the ocean. However, the use of Th-234 in the ocean has been hampered by labor-intensive procedures, low throughputs, and large uncertainties related to source impurities. Here, we demonstrate a more efficient technique developed to analyze Th-234 in seawater by modifying the traditional Fe(OH)(3) co-precipitation method. The advantages and shortcomings of this method were compared with the Th-234 analytical method using MnO2 precipitation. In the new method, following the equilibration of the Th-230 spike with Th-234, Th was co-precipitated with Fe. Although the precipitates include a fraction of U, Fe precipitation was fast, and the supernatant can be easily siphoned off, allowing simple handling of several samples simultaneously. The Th adsorbed onto particles, collected by Fe precipitation, was desorbed in similar to 4 M HNO3 solution by heating at 230 degrees C for 30 min in a sealed Teflon bottle. Then, Th was separated from U using UTEVA resin. The counting source of Th was prepared by micro-precipitation of Ce. We were able to process similar to 60 samples for 5 days onboard, and the first counting was completed within a week upon returning to the laboratory. The main advantages of this method include (1) easy increase in the sample volume, (2) rapid Fe precipitation, (3) high-purity Th sources for beta and alpha counting, (4) no need for mass spectrometry, and (5) the high throughput.